474 
Agricultural Chemistry. 
instead of only about 7 tons with the superphosphate of lime 
alone. 
The addition of potass, to a mixture of superphosphate of lime 
and ammonia-salts, gives a still further increase in the case of 
wheat. With the leguminous crops we have now again a striking 
increase, and with turnips also a considerable one. 
Lastly, — a mixture of ammonia-salts, and a liberal mineral 
manure, containing superphosphate of lime, potass, soda, and 
magnesia, gives a very large increase with every one of the crops 
enumerated. The efficiency of a full supply of minerals, is seen 
to be very marked even with the cereals, when mixed with a 
large amount of the ammonia-salts ; that is to say, when these crops 
(the cereals) are supplied, at the same time, with such an amount 
of available nitrogen in the soil, as, when used alone, gives a produce 
nearly equal to that which would usually have been obtained in the 
ordinary course of farming. The mixture of ammonia-salts with mi- 
nerals does not, however, with the leguminous crops, give obviously 
more increase than when the minerals, and especially the alkalies, 
are used alone. And again, the result upon the turnips, of this 
full manuring — ^supplying as it does every important constituent 
except carbon — shows that which we have elsewhere so promi- 
nently maintained, namely, that however much the healthy growth 
of that crop may be increased by the direct use of mineral, and 
especially of pliosphatic manures, yet that for the production of a 
full crop, a supply within the soil of matter for organic formations 
is quite essential. And, had we further extended the plan of our 
Table, so as to show the effects of manures containing carbon, it 
would have been seen, as we have frequently pointed out, that 
such a supply yielded a more characteristic result Avith the 
roots than with the other crops enumerated ; next in order to 
these would probably come the leguminous crops ; and lastly 
the cereals, which are benefited least of all by manures supplying 
carbon. 
A study of this condensed summary of a vast collection of 
facts will be found highly instructive. As a main result it may 
be stated, that the average increase by mineral constituents alone 
is with the cereals less than 200 lbs., whilst with the legu- 
minous crops, even though including so many cases of really 
deficient crop arising from disease, it is four times as much. On 
the other hand, the cereal grains give an average of from 1800 
to 2000 lbs. of increase with nitrogenous manure alone ; whilst 
by the same manure there was on the average, with the legu- 
minous crops, not any increase at all. Then again, with turnips, 
we have by mineral manures alone, an average increase of gross 
produce of about 6i tons, but with ammonia-salts alone, of only 
as many hundredweights. But, if we still more carefully compare 
